Chemiluminescence during oxidation of gossipol by peroxidase]

Gossipol oxidation with peroxidase accompanied by chemiluminescence is revealed. Effect of some factors on chemiluminescence is investigated. Peroxidase gossipol oxidation is suggested to be one of the causes of spontaneous cotton root luminescence. Chemiluminescence in the system studied is inhibited by superoxide dismutase, which indicates the generation of superoxide anion radical. It is suggested that these radicals and other activated oxygen species are involved in the gossipol toxicity for parasitic microorganisms.     

Latency, without persistence, of murine cytomegalovirus in the spleen and kidney.

It is not known if murine cytomegalovirus (MCMV) establishes a state of molecular latency independent of low-level persistent infection. The presence of low levels of infectious MCMV distinguishes persistence from molecular latency. Thus, the distinction between persistence and latency has depended on the sensitivity of plaque assays for detecting low levels of infectious virus in tissue of previously infected mice. To determine whether MCMV establishes molecular latency or remains persistent, we developed two assays for detecting low levels of MCMV in tissue. Using prolonged in vitro culture of virus with either mouse embryonic fibroblasts or the murine 3T12 fibroblast cell line, we reproducibly detected a single PFU of MCMV. Inclusion of undiluted sonicated tissue in this assay decreased sensitivity by up to 100-fold. However, sensitivity was improved to 1 PFU of MCMV when sonicated tissue was appropriately diluted. Severe combined immunodeficient (SCID) mice were also used to detect MCMV in sonicated tissue. Infection of SCID mice with a single PFU of MCMV killed two of eight SCID mice, and the 50% lethal dose of MCMV in SCID mice was 2 to 3 PFU. Applying these two methods, we detected infectious virus in 0 of 34 spleens, 1 of 34 kidneys, and 0 of 37 salivary glands from latently infected mice. Spleens and kidneys assessed for persistent virus contained MCMV DNA by PCR and reactivated after 10 to 50 days in explant cultures. Latently infected kidney cells reactivated after adoptive transfer to SCID mice. Quantitation of the MCMV genome by PCR showed that latently infected spleens without detectable infectious MCMV contained about 3,000,000 copies of the MCMV genome. These results demonstrate that MCMV latency in spleen and kidney exists in the absence of low-level persistent infection. Use of assays with defined sensitivity for detection of MCMV in tissue provides a basis for evaluation of cytomegalovirus gene expression in the spleen and kidney during molecular latency.     

Ambazone as a membrane active antitumor drug

Ambazone (1,4-benzoquinone guanylhydrazone thiosemicarbazone) was found to be active against various transplantable tumors in mice as well as rats. When administered orally for 4-9 days, the effective therapeutic dose ranged between 60 and 125 mg/kg. The antineoplastic effect of ambazone appeared to be mediated, at least in part, by the immune system. In order to characterize the drug, biophysical and biophysicochemical studies were carried out using thin-layer chromatography, absorption spectroscopy and polarographic measurements. The distribution of ambazone in an n-octanol/water system indicated low hydrophobicity, thereby excluding the possibility of a preferential contribution from hydrophobic forces to the mode of action of ambazone. Ambazone undergoes three protonation reactions with pK values at 10.69 (equilibrium between the negatively charged and neutral forms), 7.39 (equilibrium between the neutral and singly positively charged form) and 6.22 (equilibrium between the singly and doubly positively charge form). Interaction of the drug with model membrane system was monitored by spectrophotometric and fluorescence measurements. Using the fluorescence label 1-anilino-8-naphthalenesulfonic acid (ANS) as a probe pointed to the interaction of ambazone with the inner area of the phospholipid bilayer matrix of liposomes as being nonspecific. Ambazone induces an overall increase in the cellular cAMP content of leukemia cells and macrophages. So far, membrane interaction has provided a molecular basis for both immunological and antineoplastic activities of the drug. By performing DNA melting experiments, it was shown that neutral or singly positively charged ambazone species stabilize the secondary structure of DNA, while the doubly positively charged form binds more strongly and destabilizes the DNA. After oral administration to rats and mice, ambazone was found to be incompletely absorbed from the gastrointestinal tract, to an extent of about 35-50%. Absorbed ambazone binds only weakly to plasma proteins, whereas its binding to red blood cells is relatively strong. The mutagenic potential of ambazone shown in bacterial systems and human lymphocytes corresponds to its relatively weak interaction with DNA. The toxic action of ambazone on the intestine is believed to be due to inhibition by the drug of bacterial DNA, RNA and protein syntheses. It is assumed that the reported affinity of ambazone for different cellular targets, i.e., membranes, nucleic acids and proteins, contributes to the overall antibacterial effect. The weak antiviral activity of ambazone in the Sendai virus/chicken embryo fibroblast system is probably the result of the interaction with Sendai virus NH glycoprotein.     

Polyacetal Carboxylic Acids: a New Group of Antiviral Polyanions

Chlorite-oxidized oxypolysaccharides are polyacetal carboxylic acids. They inhibited the cytopathic effect of vesicular stomatitis virus in mouse embryo cell cultures challenged at low input multiplicity. After intraperitoneal injection of these compounds in mice, interferon appeared in the circulation. The compounds also protected mice against lethal mengovirus infection and against the development of experimental pox lesions on the tail. Chlorite-oxidized oxyamylose was antiviral only when at least 64% of the glucopyranose units were oxidized, an observation which suggested a correlation between charge density and antiviral effect. The antiviral activity was also influenced by the molecular weight, as demonstrated by the fact that chlorite-oxidized dextrans which had a high intrinsic viscosity were more active than those with low intrinsic viscosity.     

Inhibition of retrovirus-induced disease in mice by camptothecin.

We have previously shown that noncytotoxic doses of camptothecin (CPT), a topoisomerase I-specific antagonist, inhibit retrovirus replication in acutely and chronically infected cells. To evaluate the efficacy of CPT as an antiretroviral drug in vivo, we injected newborn BALB/c mice with Moloney murine leukemia virus and adult NFS mice with Friend spleen focus-forming virus. The Moloney murine leukemia virus-injected mice developed lymphoma, and the Friend spleen focus-forming virus-injected mice developed erythroleukemia. CPT, administrated together with the virus or 1 or 2 days after virus injection, prevented the onset of the disease in both cases. We showed that repeated CPT treatments increased the effectiveness of the drug when administrated 3 days after virus injection. This ability of CPT to inhibit retrovirus-induced disease in vivo without causing any apparent toxic side effects suggests its application as a legitimate remedy for the treatment of retroviral diseases.     

Further characterization of the polyoma virus Y8e from a Rauscher leukaemia virus producing mouse cell line and detection of partial sequence homology between polyoma virus Y8eDNA and hamster papovavirus DNA.

A DNA virus of the papovavirus group spontaneously appeared in RLV-infected spleen and thymus cells of mice in vitro was further characterized as polyoma virus Y8e by haemagglutination test, banding in density gradients, sedimentation coefficients of DNA and molecular hybridization of its DNA. The latter technique showed nearly complete sequence homology to polyoma virus strain SE DNA, partial sequence homology to hamster papovavirus DNA and mouse host DNA and little or no sequence homology to SV 40 DNA. The relationship between rodent papovaviruses and primate papovaviruses is discussed.     

Sexual transmission of hepatitis C virus and its relation with hepatitis B virus and HIV.

OBJECTIVE--To determine the extent of transmission of hepatitis C virus in sexual partners of intravenous drug misusers and to examine the relation between the prevalences of HIV, hepatitis B virus, and hepatitis C virus infections in homosexual men and intravenous drug misusers and their sexual partners. DESIGN--Serum samples collected between 1984 and 1988 were tested for hepatitis B virus markers and antibodies against hepatitis C virus by enzyme linked immunosorbent assay (ELISA) and for HIV antibody by enzyme immune analysis and western blotting. SETTING--Large referral university hospital with an external AIDS clinic in the metropolitan area of Barcelona, Spain. SUBJECTS--243 Intravenous drug misusers, 143 of their regular heterosexual partners, and 105 homosexual men. MAIN OUTCOME MEASURES--Prevalences of hepatitis C virus, hepatitis B virus, and HIV infections. RESULTS--In all, 178 of the 243 (73%) intravenous drug misusers, 16 out of 143 (11%) of their partners, and 17 of the 105 (16%) homosexual men had antibodies against hepatitis C virus. The presence of hepatitis C virus infection was unrelated to sex, age, the presence of HIV or hepatitis B virus infections, or the Centers for Disease Control stage of HIV. In sexual partners of intravenous drug misusers there were strong correlations between the presence of hepatitis C virus infection and that of HIV (p = 0.001) and hepatitis B virus (p = 0.013) infections. CONCLUSIONS--Intravenous drug misusers have a high risk of acquiring hepatitis C virus, hepatitis B virus, and HIV infections, but the presence of hepatitis C virus infection seems to be unrelated to the presence of the other two viruses. Homosexual men have a high prevalence of HIV and hepatitis B virus infections with a low prevalence of hepatitis C virus infection, the presence of which is not related to that of the other two infections. Conversely, heterosexual partners of intravenous drug misusers have low prevalences of the three virus infections, but the presence of hepatitis C virus infection correlates significantly with the presence of HIV and hepatitis B infections. The rate of sexual transmission of hepatitis C virus seems to be low, even in partners of people known to be seropositive for this virus.     

Determination of Paclitaxel Distribution in Solid Tumors by Nano-Particle Assisted Laser Desorption Ionization Mass Spectrometry Imaging

A sensitive, simple and reproducible protocol for nanoparticle-assisted laser desorption/ionization mass spectrometry imaging technique is described. The use of commercially available TiO₂ nanoparticles abolishes heterogeneous crystallization, matrix background interferences and enhances signal detection, especially in the low mass range. Molecular image normalization was based on internal standard deposition on tissues, allowing direct comparison of drug penetration and distribution between different organs and tissues. The method was applied to analyze the distribution of the anticancer drug paclitaxel, inside normal and neoplastic mouse tissue sections. Spatial resolution was good, with a linear response between different in vivo treatments and molecular imaging intensity using therapeutic drug doses. This technique distinguishes the different intensity of paclitaxel distribution in control organs of mice, such as liver and kidney, in relation to the dose. Animals treated with 30 mg/kg of paclitaxel had half of the concentration of those treated with 60 mg/kg. We investigated the spatial distribution of paclitaxel in human melanoma mouse xenografts, following different dosage schedules and found a more homogeneous drug distribution in tumors of mice given repeated doses (5×8 mg/kg) plus a 60 mg/kg dose than in those assigned only a single 60 mg/kg dose. The protocol can be readily applied to investigate anticancer drug distribution in neoplastic lesions and to develop strategies to optimize and enhance drug penetration through different tumor tissues.     

Anomalous behavior of the major avian myeloblastosis virus glycoprotein in the presence of sodium dodecyl sulfate.

The sodium dodecyl sulfate (SDS) complex of the major glycoprotein of avian myeloblastosis virus exhibited an anomalously low free electrophoretic mobility compared with those of non-glycosylated protein standards. The apparent molecular weight of the glycoprotein calculated from the relation between log molecular weight and electrophoretic mobility depended on the acrylamide concentration and reached a lower limit of 80,000. The molecular weight was also estimated from the retardation coefficients of protein standards and the viral glycoprotein. This method yielded a molecular weight of 64,000 for the avian myeloblastosis virus glycoprotein. When gel chromatography in SDS was used to determine the apparent molecular weight of the glycoprotein from its hydrodynamic properties alone, the estimated value was 50,000. The generally assigned value of 80,000 daltons for the avian myeloblastosis virus major glycoprotein, as determined by SDS electrophoresis, may be an overestimate due to its relatively low free electrophoretic mobility and peculiar conformation in SDS.     

A novel TK-NOG based humanized mouse model for the study of HBV and HCV infections

The immunodeficient mice transplanted with human hepatocytes are available for the study of the human hepatitis viruses. Recently, human hepatocytes were also successfully transplanted in herpes simplex virus type-1 thymidine kinase (TK)-NOG mice. In this study, we attempted to infect hepatitis virus in humanized TK-NOG mice and urokinase-type plasminogen activator-severe combined immunodeficiency (uPA–SCID) mice. TK-NOG mice were injected intraperitoneally with 6 mg/kg of ganciclovir (GCV), and transplanted with human hepatocytes. Humanized TK-NOG mice and uPA/SCID mice were injected with hepatitis B virus (HBV)- or hepatitis C virus (HCV)-positive human serum samples. Human hepatocyte repopulation index (RI) estimated from human serum albumin levels in TK-NOG mice correlated well with pre-transplantation serum ALT levels induced by ganciclovir treatment. All humanized TK-NOG and uPA–SCID mice injected with HBV infected serum developed viremia irrespective of lower replacement index. In contrast, establishment of HCV viremia was significantly more frequent in TK-NOG mice with low human hepatocyte RI (<70%) than uPA–SCID mice with similar RI. Frequency of mice spontaneously in early stage of viral infection experiment (8 weeks after injection) was similar in both TK-NOG mice and uPA–SCID mice. Effects of drug treatment with entecavir or interferon were similar in both mouse models. TK-NOG mice thus useful for study of hepatitis virus virology and evaluation of anti-viral drugs.     

A thiopurine drug inhibits West Nile virus production in cell culture, but not in mice

Many viruses within the Flavivirus genus cause significant disease in humans; however, effective antivirals against these viruses are not currently available. We have previously shown that a thiopurine drug, 6-methylmercaptopurine riboside (6MMPr), inhibits replication of distantly related viruses within the Flaviviridae family in cell culture, including bovine viral diarrhea virus and hepatitis C virus replicon. Here we further examined the potential antiviral effect of 6MMPr on several diverse flaviviruses. In cell culture, 6MMPr inhibited virus production of yellow fever virus, dengue virus-2 (DENV-2) and West Nile virus (WNV) in a dose-dependent manner, and DENV-2 was significantly more sensitive to 6MMPr treatment than WNV. We then explored the use of 6MMPr as an antiviral against WNV in an immunocompetent mouse model. Once a day treatment of mice with 0.5 mg 6MMPr was just below the toxic dose in our mouse model, and this dose was used in subsequent studies. Mice were treated with 6MMPr immediately after subcutaneous inoculation with WNV for eight consecutive days. Treatment with 6MMPr exacerbated weight loss in WNV-inoculated mice and did not significantly affect mortality. We hypothesized that 6MMPr has low bioavailability in the central nervous system (CNS) and examined the effect of pre-treatment with 6MMPr on viral loads in the periphery and CNS. Pre-treatment with 6MMPr had no significant effect on viremia or viral titers in the periphery, but resulted in significantly higher viral loads in the brain, suggesting that the effect of 6MMPr is tissue-dependent. In conclusion, despite being a potent inhibitor of flaviviruses in cell culture, 6MMPr was not effective against West Nile disease in mice; however, further studies are warranted to reduce the toxicity and/or improve the bioavailability of this potential antiviral drug.     

Transgenic mice with intracellular immunity to influenza virus

We have generated transgenic mice that express the intracellular anti-influenza virus protein Mx1 under control of an interferon-responsive regulatory element. Upon infection with influenza virus, mice of a high responder line produce Mx1 protein locally at the sites of initial viral replication, exhibit little viral spread, and survive infection. Mice of a low responder line show more extensive viral spread and survive infection only when virus is given at high doses. To survive low dose infections, these mice require injection of interferon along with virus. The results show that influenza viral pathogenesis is determined by a subtle balance between the dose of the infecting virus and the levels of the antiviral host factor Mx1 and that mice can be rendered resistant to a virulent infection by "intracellular immunization" achieved through germline transformation.     

A direct demonstration of recombination between an injected virus and endogenous viral sequences, resulting in the generation of mink cell focus-inducing viruses in AKR mice.

We analyzed viral recombination events that occur during the preleukemic period in AKR mice. We tagged a molecular chimera between the nonleukemogenic virus Akv and the leukemogenic mink cell focus-inducing (MCF) virus MCF 247 with an amber suppressor tRNA gene, supF. We injected the supF-tagged chimeric virus that contains all of the genes of MCF 247 except the envelope gene, which in turn is derived from Akv, into newborn AKR mice to evaluate its pathogenic potential. Approximately the same percentage of animals developed leukemia with similar latent periods when injected with either the tagged or nontagged virus. DNA from tumors induced in AKR mice by the tagged chimeric virus was analyzed by Southern blotting with the supF gene as a probe. One set of tumors contained the injected supF-tagged virus. Two kinds of supF-tagged proviruses were found in a second set of tumors. One group of supF-tagged viruses had a restriction map consistent with that of the injected virus, while the other group of proviruses had restriction maps that suggested that the proviruses had acquired an MCF virus-like envelope gene by recombination with endogenous viral sequences. These results demonstrate that injected viruses recombine in vivo with endogenous viral sequences. Furthermore, the progression to leukemia was accelerated in mice that develop tumors containing proviruses with an MCF virus env gene, emphasizing the importance of the role of the MCF virus env gene product in transformation.     

Pattern recognition molecule mindin promotes intranasal clearance of influenza viruses

The innate immune response is essential for host defense against microbial pathogen infections and is mediated by pattern recognition molecules recognizing pathogen-associated molecular patterns. Our previous work has demonstrated that the extracellular matrix protein mindin functions as a pattern recognition molecule for bacterial pathogens. In this study, we examined the role of mindin in influenza virus infection. We found that intranasal infection of mindin-deficient mice by influenza virus resulted in dramatically increased virus titers in the lung and intranasal cavity of mutant mice. In contrast, lungs from intratracheally infected mindin-deficient mice contained similar influenza virus titers. We showed that mindin interacted with influenza virus particles directly and that mindin-deficient macrophages exhibited impaired activation after influenza virus infection in vitro. Furthermore, intranasal administration of recombinant mindin significantly enhanced the clearance of influenza virus in wild-type mice. Together, these results demonstrate that mindin plays an essential role in the host innate immune response to influenza virus infection and suggest that mindin may be used as an immune-enhancing agent in influenza infection.     

Lipolysis induction in adipocytes by a protein from tumor cells

Extracts of thymic lymphoma that are obtained from AKR mice and are kept in the cold for at least several days can induce lipolytic activity in rat adipocyte suspensions. Freshly prepared extracts have low activity but contain a low molecular weight material of less than 10,000 daltons that aggregates on standing in the cold and becomes active. Treatment of aged extracts with trypsin causes a loss in activity indicating that the active material is a protein. It has been obtained in partially purified form, is relatively heat stable, and is not a lipase. Activity was also demonstrated in AKRXDBA/2 lymphoma (induced by AKR SL3-3 virus) and in transplanted lymphomas from a Friend-virus-induced erythroleukemia cell line in DBA/2 mice, but was not detected in normal thymus, spleen, liver, or other tissues. The partially purified material produced a massive fat mobilization when injected into normal mice.     

IFN和PDS合剂体内抗流感病毒的作用

观察了IFN与PDS合剂的体内抗病毒效果。首先排除IFN和PDS对动物的毒性作用 ,再以不同剂量的单剂和合剂给小鼠用药。用流感强毒株对小鼠进行攻击 ,同时以利巴韦林和正常小鼠作为对照。通过对动物死亡率、肺部病变的病理组织学检查结果进行比较 ,合剂组效果明显好于单剂组 ,且有剂量效应关系。上述结果表明 ,IFN和PDS合剂可明显减轻流感病毒感染过程中的肺组织病变 ,可用于流行性感冒的治疗。     

Dobrava, but not Saaremaa, hantavirus is lethal and induces nitric oxide production in suckling mice

Hantaviruses are the causative agents of HFRS and HCPS (hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome), two severe, and often fatal human diseases. Mortality from HFRS varies between hantaviruses; Hantaan and Dobrava show the highest, Seoul intermediate, and Puumala low mortality. Saaremaa, genetically closely related to Dobrava, is also known to induce HFRS, with low or no mortality. In this study, mice were inoculated with Dobrava and Saaremaa viruses to test for infectibility, lethality, viremia, nitric oxide production and antibody responses. Out of suckling mice intracerebrally inoculated with 50, 500 and 5,000 focus-forming units of Dobrava virus, respectively, 1/8, 2/8 and 7/8 died within 18-26 days. In all but one of the lethally infected mice high levels of replicating virus were detected, and most were positive for neutralizing antibodies and showed elevated levels of nitric oxide production. All suckling mice intracerebrally inoculated with 50, 500, or 5,000 focus-forming units of Saaremaa virus survived and all seroconverted. Clearly lower viral titers were observed for the Saaremaa virus-inoculated mice, also when sacrificed at day 18 after infection, compared to those in mice that died following Dobrava virus infection. Dobrava, Saaremaa, Puumala and Hantaan virus infections of adult mice were asymptomatic, and the anti-nucleocapsid protein IgG2a/IgG1-titer ratio was higher in mice inoculated with Dobrava virus than in those inoculated with Saaremaa virus. Elevated nitric oxide production was not detected in asymptomatically infected mice, and iNOS-/- mice, like normal mice, cleared viremia. In conclusion, we show that Dobrava virus and Saaremaa virus induce distinct differences in terms of survival, viremia, nitric oxide production and antibody responses in mice.     

Murine Mammary Tumor Virus Expression During Mammary Tumorigenesis in BALB/c Mice

Steady-state levels of murine mammary tumor virus (MuMTV) RNA were quantitated during mammary tumorigenesis in BALB/c mice by molecular hybridization with a representative MuMTV complementary DNA (cDNA) probe. Hyperplastic alveolar nodule (HAN) lines are preneoplastic mammary lesions that were induced in BALB/c mice by hormones alone or in combination with 7,12-dimethylbenz(a)anthracene and give rise to mammary tumors. The hormone-induced HAN lines D1 and D2 contained detectable amounts of hybridizable MuMTV sequences. MuMTV RNA sequences were also observed in five of the six transplanted BALB/c mammary tumors that were examined. Similar levels of hybridizable MuMTV RNA were observed between the D1 or D2 HAN line and mammary tumors derived from each HAN line. The D2 HAN line as well as D2, C4, and CD8 mammary tumors accumulated RNA that was apparently homologous to most of the MuMTV genome. Thermal denaturation of hybrids indicated extensive sequence homology between the MuMTV cDNA and hybridizable RNA in the BALB/c HAN lines and mammary tumors. A low level of type C viral RNA was observed in the BALB/c HAN lines and most mammary tumors by molecular hybridization with a cDNA to Moloney murine leukemia virus. These data demonstrate that MuMTV sequences are frequently expressed in hormone-induced BALB/c HAN lines and mammary tumors derived from HAN lines or ductal hyperplasias induced in BALB/c mice by hormones and/or a chemical carcinogen. The transition from the preneoplastic to the neoplastic state in BALB/c mice does not appear to be due to a change in the steady-state levels of MuMTV RNA since the hormone-induced HAN lines and mammary tumors had similar levels of hybridizable MuMTV RNA.